Shoulder prostheses are known, which comprise glenoid supports that are attached in the glenoid bone seating of the shoulder blade and allow attachment and anchorage to a shoulder blade, depending on whether it is an inverse or anatomical prosthesis, either a convex glenoid head, or a cup or a concave glenoid insert.
Known glenoid supports normally comprise a substantially flat, or at most slightly concave, attachment plate normally quadrangular or polygonal, comprising in a single piece an anchoring element, mainly cylindrical in shape, able to be attached in a corresponding seating provided in the glenoid cavity itself.
The anchoring element and/or the attachment plate can be provided with surface elements (or linings) able to promote the process of osteo-integration and to allow a greater stability of attachment inside the seating.
The attachment plate can be provided with holes to attach it to the bone using screws.
The shape and sizes of the glenoid support, and hence of the attachment plate and the anchoring element, must be chosen by the surgeon according to the particular bone conformity of the shoulder blade in which the glenoid support is to be applied, in order to optimize the implant operations and to promote the process of osteo-integration.
This implies that different glenoid supports must be prepared and made available for the surgeon, having different shapes and sizes of the attachment plate and the anchoring element, which are chosen on each occasion by the surgeon.
Furthermore, even when the condition of the bone is substantially normal, it may be difficult for the surgeon, given the extremely limited space available and the bulk of the attachment plate, to intervene with the appropriate surgical instruments in order to position and attach the whole glenoid support inside the shoulder blade precisely.
Another disadvantage of known solutions is when the prosthesis has to be checked, or when a prosthesis that was originally anatomical must be replaced by an inverse prosthesis, or vice versa, due to the difficulty of removing from the bone seating the connection between the glenoid support and the relative articulation element, whether it is concave or convex, depending on the case.
Document FR-A-2.579.454, on which the preamble to the main claim is based, shows a glenoid support in which the anchoring element and the relative plate are made in two different parts: the anchoring element has an axial cavity and is threaded externally to be attached by screwing into a bone seating already prepared, and the plate is made in two parts which can be made solid with each other using screws, and is anchored outside the neck of the shoulder blade by means of flanges that allow attachment screws to be inserted.
This solution only concerns prostheses of the anatomical type, and has an anchoring and assembly configuration that in practice renders the glenoid elements difficult to remove and/or replace without intervening very invasively on the bone part on which they are anchored.
One purpose of the present invention is to achieve a glenoid element that allows the surgeon, during the implant operations, an easy and precise positioning and correct attachment of the glenoid support in a suitable seating made in the shoulder blade.
Another purpose of the present invention is to facilitate the primary attachment of the component and its subsequent oste-integration by means of suitable fastening means suitably made on the surface of the plate and/or the anchoring element.
Another purpose of the present invention is to make a glenoid support of the modular type, which facilitates the choice of the attachment plate and also the type of anchoring element to be applied to the shoulder blade, both according to the particular bone conformation of the shoulder blade, and also the type of prosthesis to be applied, for example anatomical or inverse.
This modularity also facilitates checking the component, making it easier, less invasive and allowing the possibility of choosing the size and type of the plate and the anchoring element also in the event of a second implant.
A further purpose of the present invention is to optimize the working times and processes of the glenoid support, achieving dedicated production lines for the common workings of at least one of its parts.
Another purpose of the present invention is to achieve a glenoid support simply and economically, without in any way affecting the correct functioning of the prosthesis in its entirety.
Another purpose is to facilitate the removability and replaceability of the components, and also to allow the possibility of passing from a prosthesis of the anatomical type to one of the inverse type, or vice versa, without requiring particularly invasive interventions on the bone part of the glenoid cavity where the prosthesis is positioned.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.